Polymerization of indene



17, F. J. SODAY' POLYMERIZATION 0F INDENE Filed Aug. 16, 1939 Nm. Nm.

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enema Api. 11, 194s UNITED STATES PA'ragr omer.

PQLYmIZAl'ION 0F INDENE Frank J. Soday, Upper Darby, Pa., assigner .to

. The United Gas Improvement company, a cory poration of Pennsylvania Application August 18, 1939, Serial No. 290,503

s claims. (ci. zoo-so) v This invention relates to the preliltion of indene polymers by the polymerizatiomby means v of a catalyst selected from the class consisting of alkyl and aryl acid sulfates, of indene which is substantially free from coumarone, including pure indene, and `including hydrocarbon fractions containing indene but substantially free from coumarone.

Indene is an unsaturated hydrocarbon, the

structureof which may be represented as foilows:

n C/ i.

l s In its purified form, indene is a colorless, oily liquid boiling at 182 C., solidifying at 2 C. and

having a specific gravity f 0.9910 at 15 C.

Indene occurs generally in coaltar and in hydrocarbon fractions obtained in the distillation y, of coal tar, particularlyl the higher boiling unsaturated fractions commonly referred to as crude solvent naphtha. o p Y In such fractions, indene is often associated with coumarone, an oxygen containing unsaturated compound having a structural formula somewhat similar to indene, as follows:

Hydrocarbon fractions containing indene may ybe utilized for the production of resinous polymers by effecting polymerization of the unsaturated constituents of such fractions.

In the manufacture of artificial gases such as coal gas, oil gas and carburetted water gas, considerable quantities of tar are produced and the gas contains "substantial quantities of readily condensable materials. Indene may generally be found in the condensate and in the light oil obtained upon distillation of these various tars.

Fractionation of light oil from coal gas, oil gas or carburetted water gas yields fractions, the

higher boiling of which contain large concentrations of indene. Pure indene may be' obtained from these fractions by further treatment using Generally 'speaking.- fractions obtained from oil gas or carburetted water gas manufacture do not contain coumarone, as does a fraction obtained from cosi gas msnufacme.- As is or course well known in the gas making art, the manufacture of oil gas or carburetted water gas involves the pyrolytic decomposition of petroleum vndene or hydrocarbon fractions containing insolubility in the usual solvents,

indene and hydrocarbon fractions containing indene, may be polymerized to yield resinous materials by contacting with sulfuric acid.4 However, the polymerization of indene with sulfuric acid is a highly exothermic reaction and is thus very difficult to control. There is a pronounced tendency for the reaction temperature to increase at a very rapid rate at certain stages of the polymerization resulting in the production of a relatively large proportion of sludge, as well as the production of a dark colored resin of inferior Furthermore, unduly large losses. of reactive material in the form of sludge results from undesirable side reactions whensulfuric acid is used as a catalyst for indene polymerization. This is due to an intense local .superheating in various portions of the reacting' material during the course of the reaction. 'Ihe recovery and puriilcation of the resinous polymers from the poLymerized material obtained under these conditions is an extremely dimcult undertaking. In addition, the resin obtained is frequently of such character as to be of little value for many industrial applications such as, for example, the preparation of coating compositions.

I have found that the polymerization of substantially coumarone-free indene including pure coumarone-free indene. generally may be prepared by the reaction of sulfuric acid or sulfonating agents upon ethers, alcohol, esters, and oleiines.

Although `alkyl and aryl acid sulfates suitable for use as indene polymerization catalysts may be prepared by any fthese methods, the use of v organic ethers has been found to be a particularly convenient and advantageous method for their production.

' The reaction products of ethers and sulfuric acid are highly desirable as polymerization catalysts, not only because of their property of producing light colored indene resins `of good quality when employed in accordance with my invention, but also because of their stability. Such catalysts may be stored for relatively long periods of time without any serious loss of catalytic activity.

When the indene polymerization catalysts are prepared from organic ethers, various alkyl, arylalkyl, and aryl ethers may, be used. 'Ihe choice Cs-O- CsHs Diothyl other on on.

Dlisopropyl other Among the aryl-alkyl ethers which aresuitable for the production of indene polymerization catalysts may be mentioned, as examples, anisole and phenetole, having the following general structural formulae:

' o-cm Anlsole O-CsHs Phenetole Ilustrative of the aryl'ethers which may be reacted with sulfuric acid to produce desirable indene polymerization catalysts may be mentioned, among others, diphenyl oxide having the following general structural formulae:

Diphenyloxide In addition to ethers. other organic compounds may be reacted with sulfuric acid to produce suitable catalysts for the polymerization of indene.

For example, the reaction of sulfuric acid in -in detail hereinafter.

` Various methods for the preparation of organic acid sulfates suitable for the catalysis -of indene polymerization reactions lwill be discussed more The polymerization is preferably carried out by the addition of the catalysts to the indene or mixture containing. indene although other methods maybe used if desired.

The exact mechanism of the polymerization of indene is unknown. It is believed, however, that the reaction proceeds stepwise by the regular addition of successive molecules of the monomer to the double bond present at the stage `of polymerization immediately preceding. The

resulting, Polymer presumably has the following configuration.

t its l is particularly adapted to the preparation of alcohols produces alkyl or aryl hydrogen sulfates which are also effective as indene polymerization catalysts. Illustrative of the suitable a'lcohols may be mentioned, among others, ethyl alcohol and isopropyl alcohol.

The reaction products of sulfuric acid and organic esters such, for example, as ethyl acetate, methyl acetate, and isopropyl acetate, are highly satisfactory as indene polymerization catalysts.

Generally speaking. the essential constituent of the catalysts which may be used for the polymerization of substantially coumarone-free indene and of indene-containing hydrocarbon fractions substantially free from coumarone is an alkyl'or aryl acid sulfate. This is generally the case regardless of the materials from which such catalysts are prepared, the method of their preparation or the nature and relative proportions of any other components with which such catalysts may be associated.

The nature of the indene-containing fraction to be polymerized will determine to a large extent the manner in which the catalysts will be prepared inV order to secure a polymerization' product of the desired quality.

indene polymers from hydrocarbon fractions containing indene and substantially free from coumarone, pure indene and other fractions containing high concentrations of indene and substantially free from coumarone may be utilized with the production of desirable resinous products.

In order to Ainsure the production of lightcolored high melting resins, the temperature of the polymerization reactionshould be controlled within fairly narrow limits. Y

In general, polymerizing temperatures inthe range of 0 to 50 C. are preferred, and particularly temperatures within the range of l0 to 30 C.

The use of aryl and alkyl acid sulfates as in- -dene polymerization catalysts, generally speaking, makes unnecessary any external means of cooling the reaction mixture.

However, the reaction mixture may, if desired, be cooled during the course of the reaction to prevent the development of excessive temperatures.

Among other ways, such cooling may be effected by circulating a cooling medium. through cooling coils immersed in the reaction vessel, circulating a cooling medium around the outer surfaces of the reaction vessel, or the reaction mixture may be circulated through external condensers during the course of the reaction.

It isgenerally desirable to thoroughly agitate the reaction mixture during the polymerization process in order to maintain an even temperature throughout.

Generally speaking, when the material to be polymerized contains a high concentration of indene, an inert solvent is preferably added therevto as a diluent before the addition of the catcatalyst during the course of the polymerization.

Illustrative of the hydrocarbon solvents may be mentioned, among others, benzene, toluene, xylene, petroleum ether, petroleum naphtha, soivent naphtha, and heptane. v

Illustrative of chlorinated solvents which may be used as diluents may be mentioned, among others, chloroform, carbon tetrachloride, ethyl'- ene dichloride, and chlorobenzene.

The use of such inert solvents is also advantageous after a hydrocarbon fraction containing a high concentration of indene, foi example, pure indene, has been polymerized. The reaction product of such a polymerization, generally speaking, is solid or highly viscous and in such case may be relatively diilicult to purify. When it is desired to polymerize substantially pure indene or hydrocarbon fractions containing high concentrations of indene, but substantially free from coumarone, suitable solvents such as, for example, any of the solvents hereinabove enumerated, may be utilized to dissolve the solid or highly viscous reaction mass,v after which the purification may proceed-in the usual way.

In the practice of the process, the polymerization reaction may be carried out batchwise in suitable containers, or various continuous or semi-continuous methods may be utilized.

The quantity of alkyl or aryl acid sulfate catalysts which may be used to effect polymerization of hydrocarbon fractions containing indene but substantially free from coumarone, is not critical. Generally speaking, approximately 1 to 10% by volume of catalyst -based upon the indene present in the mixture undergoing Polymerization will be found suilicient in most cases, a1- though larger quantities of catalyst may be employed if desired, particularly for the polymerization of fairly dilute solutions.

After the completion of the reaction, the polymerized mixture is generally allowed to settle for a short :period of time, after which the catalyst layer may be drained oil or removed by other suitable methods.

'I'he remaining traces of catalyst may then be ,removed by neutralization with alkaline solutions, such as, for example, aqueous sodium carbonate, sodium hydroxide, or lime solutions, or with various contact materials, such as, for example, clay, fullers earth, .diatomaceous' earth, alumina, silica, or similar materials.

Various combinations of these methods may also be employed to remove the remaining traces of catalyst with equally good results.

For. example, the polymerized solution may be neutralized with an aqueous sodium carbonate solution, followed by the removal of thewater layer, and the application of clay. After the removal of the clay, the solution will be found to be light in color and completely neutralized.

In general, neutralization with contact agents such as clay may be normally carried out at elevated temperatures, such as for example, 10o to 110,C. 1 a

The ease with which the polymerized solutions resulting from this process may be neutralized is a valuable characteristic of the present invention.

Under prior art methods, when sulfuric acid was used for the polymerization of indene and coumarone in hydrocarbon fractions the polymerized solution, generally speaking, could not be completely neutralized by the application of clay alone due to the presence of excessive quantities of acid sludge and sulfonated materials.

. 3 However, when alkyl or aryl acid-sulfate! are employed as catalysts for the polymerization of indene substantially ireefrom coumarone, under normal polymerizing conditions, the catalyst may be completely removed at the end of the poly- `mer'lzing process by treatment with clay.

'Ihe use of alkyl or aryl acid sulfates'as catalysts, when polymerizing substantially coumarane-free indene according. to my invention,

tilled in order to remove unpolymerized mate-- avoldsthe necessity of using alkaline solutions to effect neutralization.

Alkaline solutions may, of course, be used. if desired, either alone or in commotion with the use of other neutralization agents such as clay.

The polymerized solution is preferably disrial, as well as to afford a separation between the liquid polymers, commonly referred to as heavy oil, 'and the solid resinofus polymers. In general, however, only very small quantities of the liquid polymers are normally obtained in. the practice of my invention. V

The distilling and hardening operations may be carried out in any suitable manner, such as, for example, distillation under reduced pressure.

Steam distillation, using either saturated or superheatedy steam, may also be employed in the distilling and hardening operations with excellent results, especially when carried out under reduced pressure.

The indene resins obtained as a result of the process outlined herein are. generally speaking, light in color, compatible with varnish oils and the usual solvents, and have fairly high melting y points. They may be used for the preparation of oil varnishes, spirit varnishes, paints, lacquers, enamels, and coating compositions in general. 'They have excellent water and alkali resistance and can be used to advantage for applications 40 requiring a coating with good dielectric properties. v l' One exemplary method for carrying out the process may be to proceed in a semi-continuous manner, starting initially with the formation of the organic acid sulfate catalysts, and proceeding through the polymerization of the indene to the separation of the liquid and solid polymer products.

Such a vprocedure is diagrammatically illustrated in thevaccompanying figure, where there is shown apparatus for the production of an organic acid sulfate catalyst, and connected therewith, apparatus for the polymerization of hydrocarbon fractions containing indene and substantially free from coumarone, apparatus for the neutralization and purification of the polymerized reaction product, and apparatus for the separation of the various polymer products thus produced.

Coming now tothe initial step in such a procedure, namely that of preparing the catalyst, it has been pointed out above that one convenient method, among others, for the preparation of alkyl or aryl "acid sulfate catalysts is to react `sulfuric acid with an organic ether selected from the class consisting of alkyl, aryl-alkyl, and aryl ethers.

While this reaction lmaybe carried out in any desired manner, a preferred'method comprises mixing the desired ether with the sulfuric acid at room temperature, followed by heating to a temperature sufficiently high to promote the re- A action between the sulfuric acid and the ether The temperature, however, should not be in-` creased to such a 'point as to cause any appreciable decomposition of the ether or the substituted sulfuric acid catalyst subsequently obtained.

' The proportions of acid and ether used in the preparation of the catalyst may be varied over very wide limits, the properties of the resulting catalyst depending in part on the proportions utilized.

A particularly stable catalyst for the polymerization of indene substantially free from coumarone and one ing good polymerizing properties. may be prepared by reacting sulfuric acid with the desired ether in proportions of approximately two mois of acidl to approximately one mol, or slightly less, of ether.

An indene polymerization catalyst prepared in this manner may be stored for relatively 1mg pe'- riods of time without any serious loss of its catalytic activity.

While the exact nature of the reaction by which the indene polymerization catalysts herein described are formed, by the action of the sulfuric acid upon organic ethers, has not been definitely determined, the following is offered as a possible explanation.

An ether, such, for example, as diethyl ether is believed to first react with the sulfuric acid to form ethyl hydrogen sulfate and ethyl alcohol.

Sulfuric acid is then believed to react with the ethyl alcohol to Yform additional quantities of ethyl hydrogen sulfate, together with an equixnolecular quantity of water.

These reactions indicate the products which are believed obtained when mixtures containing proportions of approximately two mois of acid per mol of ether are used in preparing the polymerization catalyst. The use of other desired proportions of acids and ethers results in the preparation of catalysts which may possess somewhat different properties.

In general. it may be said that the activity of the catalyst will depend upon the quantity of acid used in the preparation of the catalyst relative to the quantity of organic ether employed.

It is important 'to control the activity of the polymerization catalyst prepared in order to control the exothermic polymerization reaction. It will be appreciated that catalysts containing free sulfuric acid will, in general, bring about a polymerization reaction with a rapid evolution of heat.

For example, the use of larger quantities of acid than those shown above results in the production of a catalyst which consists essentially of a mixture of sulfuric acid and alkyl and/or aryl acid sulfates. This catalyst, because of its sulfuric acid content, will be more active than the catalyst previously described when used for the polymerization of indene or hydrocarbon fractions containing indene, `but substantially free from coumarone.

The use of smaller quantities of acid results in the production of a catalyst containing either free alcohol or ether or both, depending upon the ratio of the reactants employed and the conditions under which the catalyst was prepared, such as, for example, the temperature and the length of the reaction.

In general, a catalyst produced in this manner is somewhat less active than a catalyst produced by the reaction of two mois of acid with one md of ether. a

Similar reactions occur in the case of other alkyl or aryl ethers which may be used for the production of indene polymerization catalysts.

For example. when an indene polymerization catalyst is prepared through the reaction of sulfuric acid with an alkyl-aryl ether. the resulting catalyst comprises a mixture of alkyl acid sulfate and aryl acid sulfate, if the reaction is carried to completion. This is shown in the following reaction, in which phenetole is reacted with sulfuric acid.

substituted ethers may, if desired, be used in place ofv ordinary ethers with equally good results. For example, dichlorodlethyl ether may be reacted with sulfuric acid to give a suitable catalyst.

Although reference has been made more specically to the use of organic ethers for the production of indene polymerization catalysts, it is to be understood that these materials have been referred to as illustrative examples only, and that organic acid sulfates prepared in other ways, such, for example, as the reaction of sulfuric acid with oleiines, alcohols and esters, may additionally be used as effective polymerization catalysts for substantially coumarone-free lhydrocarbon fractions containing indene and for substantially coumarone-free indene generally.

In the diagrammatic flow sheet of the accompanying drawing, llv represents a reaction vessel in which the polymerization catalyst may be prepared. Sulfuric acid from the storage tank I2 and an organic ether from storage tank Il may be added to the reaction vessel il through lines il and i5 respectively controlled by valves Il and i1 respectively. The reactants may be thoroughly agitated by means of stirrer i8, if desired.

The reaction vessel il is provided with a heating and cooling chamber I9 within which there may be circulated heating or cooling media introduged through lines 2l and withdrawn through lines I.

Generally speaking, the reactants for the preparation of the indene polymerization catalysts are preferably initially contacted at room temperature, after which they are preferably heated to a temperature between 50 and 100 C. to effect the reaction. For this purpose, it may be necessary or desirable to initially flow cooling liquid through the chamber I8 while mixing the reactants, and thereafter now a heating liquid through chamber is in order to effect reaction of the sulfuric acid and the organic ether.

Line 22 connects the reaction vessel in which the catalyst may be prepared, with the polymer'- izing vessel. The indene substantially free from coumarone or the hydrocarbon fractions containing indene but substantially free from coumarone to be polymerized are preferably added to the polymerizing vessel prior to the addition of the catalyst, though this is not essential.

Line 22 is provided with valve 23 in order that the rate of addition of the catalyst to the indene fractions contained in the polymerizing vessel 2| may be controlled. Thel charge stock for the polymerizing vessel may be-supplied thereto asume nom storage tank ,as through the reed uns is' controlled by valve 21.

As has been mentioned, when pure' indene or n or cooling chamber 32 may be equipped with feed line 33 and withdrawal line 34 'for the circulation therethrough of heating and cooling liquids.

In carrying out the polymerization reaction, the desired quantity of indene, or a hydrocarbon fraction containing indene, and substantially free from coumarone may be withdrawn from its storage tank 25 and introduced into the polymerizing vessel 24 followed by the addition of solvents, if desired, from the solvent storage tank 28. The allwl or aryl acid sulfates, or mixtures containing one or both of these, may then be slowly added to the material in the polymerizing vessel 24. The temperature should be maintained at a suitable temperature, such as 20 to 30 C., during the course of addition.

The reaction is preferably'continued for anlv additional period of time to insure-the desired degree of polymerization, the temperature being maintained within a suitable range, such as 20 to 30 C. during the reaction period. The mixture is preferably continuously agitated during the course of the reaction, forexample,l by means of the stirrer 3l. After the completion of the reaction, the mixture may be allowed to settle after which the spent catalyst and sludge may be removed, for example, by means of lines 34 and 35 controlled by valve 3B.

The polymerized solution may then be transferred to the neutralizing and drying vessel 31 through lines 34 and 38, controlled by valve 39. A pump 40 may be introduced in line 38, if desired, to transfer the polymerized products to the thxihline 4I. controlled by sliding valves I4 an The further drying of the polymerized mixture may be 'omitted if desired.

The polymerized mixture may then be filtered by any suitable means, such, for example, as by forcing it through a suitable filter press l0v by means of a pump l1 inserted in lines ll and 58, the latter preferably containing a valve 53 for controlling the rate of flow of the polymerized mixture to the filter press.

After filtering, the polymerized solution may be delivered to hardening vessel l0 by means of line ll. In the hardening vessel the solvent and oily polymers may be lremoved from the solid polymers by any desired method.

I n the diagrammatic ilow sheet the separation of the oily polymers and the solvents fronrthe solid polymers is diagrammatically shown as being effected by distillation although other suitable methods may be employed.

drying lvessel 31 from the storage tank 4i through equipped with a stirrer or other agitating means 41, and with a heating and cooling chamber 48, if desired, through which may be circulated heating and coolingliquids introduced through line 49 and withdrawn through line 50.

After the neutralization of the polymerized so- -lution has been completed, any aqueous solution which may have been added may be removed through the lines 5U and 5| controlled by valve 52. The neutralized solution containing the indene polymers may then be dried, if desired, by the application of lime, stored in storage tank 53 and added to the neutralizing and drying vessel in any suitable manner suchas, for example,

The hardening vessel I0 may be equipped with a stirrer or agitating means 32. and with a heating or cooling chamber 62 through which may be circulated heating or cooling liquids introduced through lines and withdrawn through line 84. Steam may be introduced into the hardening vessel by means of the line 85 controlled by valve 68, this line preferably extending nearly to the bottom of the hardening vessel and terminating in the distribution ring 61.

After lintroduction ofthe polymerized solution into the hardening vessel 60, it may be rst distilled by the application of heat suitably under reduced pressure maintained by means of vacuum line 68 connected to a vacuum pump not show n. The vapors may be passed from the hardening vessel 60 into the distilling column 63 through line 10 and thereafter through condenser 1I connected to the distilling column by lines 12 and 13. The return line 13 may be equipped with a control valve 14.

The condensed vapor products may be collected in the liquid product receivers 1,5, connected to' the condenser by means of line 1,8 and distributing means 11 controlled by valves 18.

After the above described removal of liquid products from the polymerized mixture contained in chamber 80, steam may be introduced into the hardening vessel through line 05 and distributing means 61 to remove heavy oils. The residual polymerized mixture remaining after the hardening operation may then be transferredto the resin pan 19 through line controlled by valve 3|, and allowed to harden into the desired resinous polymer in pan 19. Valve 3| should preferably be gsitioned within the heating or cooling chamber Any desired neutralization agent or other materials for removing excess acid from the catalyst may be employed in any manner as desired. and

Although there has been described the producother methods of eifecting removal of water' from the polymerized product may be used.

Filtration of the polymerized product may be accomplished in any manner found desirable, and the resultant polymers may be purified and separated by any convenient method.

The following examples will further serve to exemplify the herein described process for the polymerization of substantially coumarone-free indene and for the preparation of indene polymerization catalysts suitable for use in the herein de 'cribed polymerization processes.

` 2 Example I Iirnately times the volume of catalyst mixture,

prepared from sulfuric acid and diisopropyl ether,

' was thoroughly mixed with an equivalent volume of xylene as a diluent. and the mixture cooled to a temperature of approximately 25 to 30 C. To this mixture there was then added the catalyst mixture slowly and with vigorous stirring. The temperature of the reaction mixture was maintained at approximately 30 C. throughout the entire reaction by circulating a cooling mixture around the outer surfaces of the POlymerizing, vessel.

After a period of approximately ilve hours, the polymerized solution was transferred to a neutralizing and drying vessel where the catalyst was neutralized by the addition of a solution of sodium hydroxide. Additional solvent was then added to the neutralized solution after which it was well washed with water and dried over lime.

The solvent and unpolymerized material was removed by distillation at a temperature of 200 C. and under a reduced pressure of approximately 20 mm. of mercury, absolute.

The residual mixture was transferred'to a resin pan and allowed to harden.

There was obtained a light-colored indene resin, soluble in the usual solvents and co patible with varnish oils.

Example I1 Approximately 700 parts by volume of an indene fraction obtained by the distillation of light oils from oil gas, and having the following properties:

Boiling range mii-18.3` C. at '760 mm. Density (D 20/4) 0.9713 Refractive index (n 20/D) 1.5600 Refractive intercept 1.0743 Indene content 83.7% by weight.

as determined by bromine titration was mixed withapproximately 500 parts by volume of high-dash petroleum naphtha in a polymerizing vessel equipped with a stirrer. To this mixture, there was slowly added with thorough agitation a catalyst prepared by reacting 50 parts by volume of sulfuric acid with approximately 45 parts by volume of diethyl ether. The polymerization was then allowed to proceed at a temperature between 20 and 2li"l C. maintained within this range by circulating a cooling medium around the outer surfaces of the polymerizing vessel. Temperature control and continual agitation was utilised to prevent au! sudden temperature surges within the polymerizing mixture.

The polymerization was allowed to proceed for a period of approximately nve hours after which the catalyst was removed therefrom and the remaining polymerized solution transferred to a neutralizing and drying vessel.

In the neutralizing and drying vessel approximately 100 parts of fuller's earth was added to polymerized mixture. It was then. heated to a temperature of approximately 100 to 110' C., for nfteen minutes and subsequently filtered. The polymerized solution thus obtained was clear and very light in color.

The poiymeriaed solution was next transferred to a hardening vessel where the volatile constituents were removed by steam distillation.

The resultant indene resin was found to be soluble in the usual solvents and compatible with varnish oils and additionally possessed highly desirable properties for industrial laipplication.

Example III Approximately 700 parts by volume of a hydrocarbon fraction containing indene. and having the same properties as those stated in Example II was mixed with approximately 500 parts by.

volume of petroleum spirits in a polymerizing vess el provided with an agitator and an external temperature control jacket. To this mixture was slowly added with constant stirring an organic acid sulfate catalyst prepared by reacting 30 parts by volume of sulfuric acid with 40 parts by volume of diisopropyl ether. The polymerization reaction was-maintained at a temperature of C. or less by circulating a cooling medium around the outer surfaces of the polymerizing vessel.

The polymerization was allowed to proceed for a period of approximately three hours, after which the spent catalyst was removed. Fuller's earth was then added to the polymerized mixture. It was then heated to to 110 C. for a period of approximately 30 minutes and snikm sequently filtered. f

There wasobtained a clear, light-colored solution of indene resin.

From the polymerized solution. the indene resin was obtained by removing the solvent by steam distillation. I'he resinous `rp'olymer thus obtained amounted to a yield of 80% of the theoretical yield calculated from the proportions of reactants employed.

This resinous polymer was very light colored and was found to be readily compatible with the usual drying oils.

Illustrative of methods for preparing organic acid sulfates, suitable as catalysts for the polymerization of substantially coumarone-free indene, are given in the following examples:

EmmplefIV Fifty parts by volume of 96% sulfuric acid was slowly added with constant agitation to approximately 45 parts Iby volume of diethyl ether in a reaction vessel provided with an agitator and a temperature control Jacket.

The temperature of the mixture of sulfuric acid and diethyl ether was maintained below 30 C. until the entire mixture had been thoroughly agitated and mixed. v

Reaction between the sulfuric acid and the diethyl ether was effected by heating the mixture of thesereactants to a temperature of approximately '70 C. for a period of approximately asvavia Example V 'I'hirty parts by weight of 66 Baume sulfuric lacid was slowly added with constant stirring to approximately 40 parts of diisopropyl ether. During the mixing of these materials the temperature was maintained at or below 30 C. After the reactants had been thoroughly mixed, the

- mixture was heated to a temperature of approximately 60 C. for a period of approximately three hours.

The resultant organic acid sulfate was found to be an excellent catalyst for the polymerization of substantially coumarone-free hydrocarbon fractions containing indene, and possessed high polymerizing activity even after storage for a relatively long period of time.

Indene polymers prepared by the process herein described possess properties which make them particularly adapted to many industrial applications. Because the polymerization of indene substantially free from coumarone may, by the process herein described, be eifected under relatively low temperature conditions, the resultant polymer is, generally speaking, found to be clear and free from color. Additionally, polymerized solutions free of acid sludge are obtained, thus resulting in greater yield of the desired indene polymer. I

Illustrative of the many applications of indene polymers prepared by the process herein described, may be mentioned the use of such polymers in coating composition formulations, partlcularly in the preparation of varnishes. Reference is made to my copending application Serial No. 481,296, filed March 31, 1943.

Illustrative of the use of an indene polymer prepared by the herein described process, is given tre following illustrative examples.

Example VI A mixture of twelve parts of indene resin, prepared as described above, and 14 parts of tung oil was heated to a temperature of approximately 400 F. during a period of approximately 20 minutes. This mixture was then heated to a temperature of approximately 560 F. during a period of ten minutes and held at this temperature for an additional period of three minutes. It was then allowed to cool to 535 F., held at this temperature for a period of six minutes, and. then chilled to a temperature of 400 F. At this temperature 26 parts of naphtha was added to reduce the varnish mixture, and thereafter the mixture was allowed to cool to room temperature. To the varnish mixture thus prepared, a desired quantity of drier was added at room temperature. A

The varnish thus obtained was a highly desirable protective coating'composition, and was almost entirely free of the usual varnish discoloration.

It will be understood that the term hydrocarbon fraction containing indene" or its equivalent, as used in the specification and claims, is intended to embrace a fraction containing indene as well as a substantial amount of other hydrocarbons. An indene fraction having the characteristics of the fraction mentioned above in Example II is one instance of a material falling within the scope of the terminology herein.

While representative procedures for the preparation of indene polymers from substantially coumarone-free indene including substantially coumarone-free hydrocarbon fractions containing indene, and for the preparation of organic acid sulfate catalysts utilized in said polymerization processes have been particularly described, it is to he understood that these are by way of illustration only. Therefore, changes, additions, substitutions, and/or modications may be made within the scope of the claims without departing from the spirit of the invention.

I claim:

1. A method comprising polymerizing indene substantially free from coumarone by contacting said indene with a catalyst selected from the group consisting of alkyl and aryl acid sulfates under temperature conditions not exceeding approximately 50 C.

2. A method of producing resinous polymer from indene substantially free from coumarone which comprises polymerzing said indene in contact with an alkyl acid sulfate catalyst under temperature conditions between approximately 0 and 30 C. throughout substantially the whole reaction mass during substantially the whole reaction period.

3. A method of producing resinous polymer from indene substantially free from coumarone which comprises polymerizing said indene in contact with an aryl acid sulfate catalyst while maintaining temperature conditions between approximately 0 and 30 C. throughout substantially the whc 1e reaction mass during substantially the whole reaction period.

4. A method for the polymerization of a light oil indene fraction substantially free from coumarone which comprises bringing a catalyst selected from the group consisting of alkyl and aryl acid sulfates into sufilcient contact with said light oil indene fraction to effect said polymerization while maintaining temperature conditions notexceeding approximately50" C. throughout substantially all of the reaction mass during substantially the entire extent of the reaction period.

5. Resin resulting from the process of claim 1.

6. Resin resulting from the process of claim 4.

7. A method comprising polymerizing indene substantially free from coumarone by contacting said indene with a catalyst selected from the group consisting of alkyl and aryl acid sulfates under temperature conditions not exceeding approximately 50 C., and in the presence of a solvent which is inert under the conditions obtaining.

8. The method of claim l in which the catalyst employed is ethyl hydrogen sulfate.

9. The method of claim 1 in which the catalyst employed is isopropyl hydrogen sulfate.

. FRANK J. SODAY. 

